The present invention generally relates to the use of lasers for measuring distances to a target.
It is common practice to use laser range finders to determine distances to a target that may be close or several hundred yards. The laser range finders are generally of two types, one of which is a phase shifting electronic measurement while the other measures the elapsed time for a signal to be propagated, reflected and detected. A common feature of either type of operation is the use of a laser beam directed to the target so that the user knows what precise target for which distance is being measured. While there is generally no difficulty in seeing where the laser spot impinges on a surface when used indoors, the ability to view a laser spot can be severely compromised in bright sunlight and at longer distances.
Some range finder users wear red colored eye glasses that can aid one to see the red laser spot in bright light conditions, while other users often also employ telescopes or other magnification to enlarge the target. Even with these aids, it is often difficult to see the laser spot. If the range finder is being used to provide important measurements, such as may be required in a construction project for example, it is important to know exactly what the target is so that the measured distance is the distance from the rangefinder to the real target of interest.
Very minor angular movement of the laser beam can greatly change the distance measurement that is being taken, particularly if a small change of angle changes the actual target that is being measured. For example, a user may want to measure the distance to a narrow column that may be several yards in front of a wall, so if the user is intending to measure the distance to the column and is actually measuring the distance to the wall, a few degrees of misalignment can result in measurement errors that can have significant adverse consequences. Even when the measurements are correct for the intended target, it can be cumbersome to provide an accurate record and description of a series of measurements.